Mechanism for operating electric switches



May 18, 1954 Filed May 31, 1951 v w. A. BLACK ETAL MECHANISM FOROPERATING ELECTRIC SWITCHES 2 Sheets-Sheet 1 qnHid (fl- Yblack CA ilk. vno le (Aw-romQY-X May 18, 1954 w. A. BLACK ETAL MECHANISM FOR OPERATINGELECTRIC SWITCHES Filed May 51, 1951 2 Sheets-Sheet 2 Nv'amwoYaA/ mmo04.61am

CA 7%. Doole v of 35 a cfl-r-ronms f Patented May 18, 1954 TENT OFFICEMECHANISM FOR OPERATING ELECTRIC SWITCHES William A. Black, Montclair,N. J and Arthur B. Poole, .Harwinton, Conn, assignors to HaydonManufacturing Company, Inc.,

Torrington,

Conn, a corporation of Connecticut Application May 31, 1951, Serial No.229,158

1 Claim.

The present invention relates to clock actuated switches and moreparticularly to a mechanism for obtaining snap action from acontinuously running clock train.

It is an object of the present invention to provide a snap actionmechanism for driving multicontact electric switches which is moresimple and compact in construction, more positive in operation, andlower in cost than preceding mechanisms of the same general type.

It is a more detailed object to provide an improved step-by-step snapaction mechanism in which friction is reduced to a minimum, which isproof against faulty operation as a result of severe shock andvibration, and in which synchronism between clock and switch isabsolutely assured.

Other objects and advantages of the invention will become apparent asthe discussion proceeds and upon reference to the drawings, in which,

Figure 1 is an exploded view of the mechanism embodying the presentinvention.

Fig. 2 is a vertical section looking edgewise at the mechanism with theparts assembled.

Fig. 3 shows a typical multi-contact cam switch arrangement suitable foruse with the mechanismof Figures 1 and 2.

Fig. 4 is a stop motion view at the beginning of a cycle of operation.

Fig. 5 is a stop motion view at the releasing point of the cycle.

Fig. 6 shows the.mechanismimmediately upon release.

While the invention is susceptible of various modifications andalternative constructions and uses, there is shown in the drawings onlyone embodiment of the invention. Itis to be understood, however, that itis not intended to limit the invention by such disclosure and the aim isto cover all modifications and alternativeconstructions and. usesfalling within the spirit and scope of the invention as expressed in theappended claim.

Referring to the drawings, the snap mechanism is included in a housing[0, which is generally cup-shaped and which has a circular mountingflange l l. The mounting flange is fastened to a mounting plate l2having an aperture l3. Extending through the aperture is an input shaftl5 which carries at its end an input or drive pinion [6. The shaft isconnected to the driving train of a synchronous clock motor (not shown).

, At the other side of the housing 10 is an output pinion I 1 whichispartially enclosedin a shield I 8. As will be covered in greaterdetail as the discussion proceeds, the output pinion I7 is advancedintermittently and with a snap-action upon continuous driving of theinput pinion. Such intermittent action is employed to operate a switchmechanism generally indicated at (Fig. 3) which is connected to thepinion H by means of a gear train 2|. The switch 20 may be of aconventional type in which the switch blades 222:i are raised andlowered by cams 25-41. Since the cam drive takes place rapidly and witha snap action the switch contacts will be operated correspondinglyquickly, thereby reducing arcing at the contacts and greatly increasingcontact life as well as improving the accuracy of the timing. Thepresent mechanism is especially applicable to switches employed inautomatic washers for controlling the washing, rinsing and centrifugaldrying cycles.

Referring now to the snap-action mechanism in greater detail, it will beseen that it includes a cam gear 30, a ratchet mechanism 3| and acircular ratch 32. The ratchet mechanism is so constructed that rotationof the cam gear causes unlocking of the ratchet with the result that theratchet mechanism is advanced periodically from one ratchet tooth to thenext upon passage of time.

The ratchet mechanism 3| includes a pawl member which is slidablymounted in a pawl carrier 4 I. For this purpose, the pawl carrier has atransversely extending body 42 and two inward- 1y turned ends 43, ,44,making the carrier of generally U-shape. In the ends 43, 44, are guidesin the form of rectangular openings 45, 46, which are alined with oneanother. The pawl member 40 has a body indicated at having outwardlyextending arms 5|, 52, which are dimensioned to be slidably received inthe openings 45, 46, of the carrier. The body of the pawl member is oflesser width than the carrier so that the pawl member is free to slideback and forth in the carrier. The path of movement is preferablydiametrical with respect to the axis of rotation of the carrier.

At the outer end of the arm 52 is a radially exw tending tooth or pawl53. The latter is of such size as to readily engage the ratchet teeth6i-8 which are internally arranged on the ratch 32.

In carrying out the invention novel means are provided for withdrawingthe pawl 53 from a given tooth upon rotation of the cam gear 39 and forsimultaneously storing up energy so that the pawl may be snapped over tothe next tooth in the series. For this purpose the cam gear 3!} includescam members .ll, 12. These cam members are spaced apart on the gear 30and are preferably formed as an axial extension of two diametricallyarranged gear teeth. For the purpose of cooperating with the cam membersll, 12 the pawl member 40 includes a curved internal cam surface 13.Such surface is so formed as to produce retraction of pawl 53 when thegear so is rotated, as will be covered in detail.

The cam surface 13 is preferably formed as one wall of a D-shapedopening indicated at 14. For the purpose of storing energy for the snapaction a spring '55 is interposed between the cam gear 30 and the pawlcarrier 41.. This spring 55 includes radially extending ends 16, H, theend I! being received in a slot 18 in the cam gear while the end itengages an inwardly turned hook 'or abutment 12s on the carrier 42. Boththe cam gear 30 and the spring it are loosely slipped over a shaft 19,which shaft is rigidly fastened to the pawl carrier ll.

When the device is assembled as shown in Fig. 2, it will be seen thatall of the parts are compactly nested together so that the totalthickness of the mechanism may be .made little more than the thicknessof a pocket watch. The cam members H, '12 are received in the opening 14in the pawl member and the pawl member itself is mounted within the pawlcarrier 41, with the pawl 53 lying in the plane of the ratchet teeth61-68.

The operation of the assembled device will be apparent upon reference toFigures 4, 5 and 6. Fig. 4 is a stop motion view showing the initialcondition of the ratchet mechanism. The pawl 53 is engaged with theratchet tooth El and the cam members H, 112 are symmetrically arrangedwith respect to the cam surface '13. The cam surface '13 is of shallowarcuate shape and is di mensioned to accommodate the cam members 1 i, 12when such cam members are arranged crosswise therein and with the pawlmember extended for engagement with a ratchet tooth. The cam surface 13is formed by two intersecting arcs with centers of curvature at 73a and130. As shown in Fig. 4, these centers 73a and E30 lie above the axis ofrotation of the'cam members H, 1.2, so that the cam members rotate aboutan axis that is eccentric with respect to the curvature of said camsurface.

The effect of this arrangement will be made clear upon reference to Fig.5, which shows the position of the members after a certain amount ofcounterclockwise movement of the cam gear Be. It will be seen in thisfigure that the cam member II has moved downwardly against the camsurface 13 with a wiping action. During such action the radius of thecam surface '13 relative to the center'of the shaft 79 becomes less andless, and continued movement of the cam gear results in the applicationof force as indicateol at 13a and the camming of the pawl member it tothe left as viewed in Fig. 5.

During the time that such movement is taking place the cam member i2moves upwardly along the right-hand portion of the cam surface 13,thereby permitting the pawl member 0 to move slowly to the left.However, it will be noted that the cam member '12 remains in contactwith the cam surface l3 as it moves upwardly, thereby preventing thepawl member from being jarred into its fully disengaged position (to theleft) as a result of shock and vibration. In brief, the pawl memberislocked with respect to: the tooth 61 and the'only thing which canunlock :it is full retraction by the .cam gear. As a result,premapractically all of the energy supplied to the meshan'ism by theclock may be usefully employed to operate the switch and a minimum ofenergy is wasted in overcoming friction.

During counterclockwise rotation of the cam gear 30, the spring 15, oneend of which is engaged with the gear 30, is tensioned, thereby applyinga progressively increasing torque to the pawl carrier 41. This torque isin such direction as to urge the pawl carrier in a clockwise oradvancing direction. The carrier is, however, locked in place until thecam gear turns through a predetermined angle. This condition is shown inFig. 5 where the pawl 53 is almostfully retracted, enabling the springto snap the entire mechanism over to the next tooth 62.

The snap action is illustrated in Fig. 6, where it will be seen that thepawl 53 is moving in the direction of the arrow into the dotted positionin which the pawl is fully seated against the tooth 52. During the snapaction practically all of the energy previously stored in the spring i5is utilized to advance the gear train 21 associated with the switch 29.To insure accurate timing, the switch cams 25-21 are preferably soarranged that drop-on of the contacts takes place at the mid-point ofthe advancing step.

During the instant of snap-over the cam members 7!, l2 remainsubstantially fixed in position and the pawl member rotates relative tothese two cam members. During such rotation the right-hand portion ofthe cam surface "53 wipes against the cam member 12. This applies .apressure against the cam surface E3, as indicated by the arrow 73b,which, as will be seen in Fig. 6, has a large component tending to forcethe cam member to the right (outwardly) for engagement with the nexttooth 6-2. The wiping action of the cam surface against the cam member12 insures that the pawl will be moved outwardly in ample time to engagethe next tooth. Thus, there is no possibility of missing a tooth andsynchronism of the clock switch is accurately maintained.

Upon'further rotation of the cam gear 30 the entire cycle of operationsoutlined above is repeated and the pawl 53 is caused to clear the tooth62, coming to rest seated against the tooth $3. The cycle is repeatedfor each of the successive teeth.

The pawl member ti) and the ratch 32 are preferably constructed of metalwhich may be hardened so that there is substantially no wear even aftermany thousands of cyclesof operation. Each of these pieces may be madeof a simple and inexpensive stamping. The pawl carrier 4| may also be ametal stamping, the blank being punched prior to inturning the endsthereof. The cam gear 36 may be simply constructed by employing an extrawide gear and then simply milling off the teeth on two opposite sides toleave only two teeth 1|, I2, which serve as the cam members.

The ratch 32 is pressed into the housing l0, being received, on asuitable internal rim or J shoulder. If desired, the circular ratch maybe locked in place by forming a groove 32a in the periphery thereof,which registers with raised internal ridge 10a on the housing II).

From the foregoing it will be seen that the entire mechanism requires noparts which are special or diificult to fabricate. It may be constructedof simple stampings and with a minimum of milling or cutting operations.Operation is positive, the intermittent advancing torque being limitedonly by the strength of the spring '15 which in turn is limited by thetorque available from the clock train. Such torque need not be great,however, since the energy which is stored up in the spring over a longperiod is released suddenly and with great force during a very shortperiod. Further, since the moving parts are light in weight andsymmetrically arranged and since the angular step is small (only 45),operation is much quieter than in snap mechanism previously employed. Inspite of its small size, it has been found that the mechanism is capableof driving large and relatively heavy switch mechanisms.

What is claimed is:

A device for converting rotary motion to reciprocating motion includinga housing, a shaft supported in said housing, a driven cam gearrotatably mounted on said shaft, said cam gear having a pair of camabutments in the form of axially extended gear teeth on opposite sidesof said cam gear, a member supported in said housing for reciprocablemovement, a curved internal cam surface on said member engaged by one ofsaid cam abutments during rotation of said cam gear to move said memberlinearly, and a second curved internal cam surface on said memberengaged by the other of said cam abutments to lock said member againstpremature movement due to shock or vibration.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 594,260 Mead Nov. 23, 1897 610,129 Ericson Aug. 30, 1898854,688 Brown May 21, 1907 1,100,515 Anderson June 16, 1914 1,369,445Kruse Feb. 22, 1921 1,479,970 Leppert Jan. 8, 1924 2,386,048 HarknessOct. 2, 1945 2,448,164 Woditsch Aug. 31, 1948 FOREIGN PATENTS NumberCountry Date 509,558 Germany Nov. 18, 1930 596,002 Great Britain Dec.24, 1947

